The capability of Doppler to detect patency of left internal mammary artery grafts through the supraclavicular approach was evaluated. A total of 37 patients with a left internal mammary artery graft to the left anterior descending artery were divided into three groups, according to postoperative coronary angiographic studies. Group 1 comprised 20 patients with no significant stenosis of the left internal mammary artery and subtotal or total obstruction in the left anterior descending coronary artery proximal to the anastomotic site. There were ten patients with no significant stenosis of the left internal mammary artery and 75% stenosis of the left anterior descending coronary artery in group 2. Seven patients with significant stenosis of the left internal mammary artery formed group 3. Analysis of the flow velocity pattern in the left internal mammary artery graft included: (1) systolic peak velocity (SPV), (2) diastolic peak velocity (DPV), (3) systolic time velocity integral (SI), (4) diastolic time velocity integral (DI), (5) diastolic peak velocity/systolic peak velocity and (6) diastolic time velocity integral/diastolic time velocity integral+systolic time velocity integral. There were no significant differences in systolic peak velocity and systolic time velocity integral between the three groups. The diastolic peak velocity and diastolic time velocity integral were greater in group 1 than in groups 2 (P < 0.05, P < 0.01) and 3 (P < 0.05). The diastolic peak velocity/systolic peak velocity and diastolic time velocity integral/diastolic time velocity integral+systolic time velocity integral ratios in group 3 were significantly smaller than in groups 1 and 2 (P < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)